It is common knowledge in the building trades and among building owners that according to the techniques of conventional building construction, walls are much more heat insulative than windows. Accordingly, in the wintertime in the cooler climates a large portion of the heat that is lost is lost through the glass of the windows.
The loss is both from conduction through the glass, which is reduced when dual glazing is used, and also there is generally at least some draft around the sides of the windows, especially in older houses. Naturally, if there is a draft, the fact that the glass itself may be dual glazed is of no help.
Applicant is inventor of a window shade sealing system which is described in U.S. Pat. No. 4,220,189. That system utilized a channel for passing around the side edges in the bottom of the shade, and a housing covering the shade roller. Although that system was quite effective, the inventor felt the need to provide a sealing system which was less bulky, and even more inexpensive.